[BUG] capture_MJPEG no timestamp

[tf4ong]

Hi,

I tried to capture_MJPEG example script for video, and added pts='timestamp.txt' in the start_recording similar to h264.

But the timestamp.txt was empty.

[chrisruk]

Thanks for reporting this, will work on this soon.

In the meantime if you add the pts parameter in this example - https://github.com/raspberrypi/picamera2/blob/main/examples/capture_mjpeg_v4l2.py you should get a timestamp.txt file.

[tf4ong]

Hi Chris,

I tried and the timestamp does seem to work but there seem to be a slight issue? I am not that familiar with codecs so it might not be concerning?

I have tried to use that script but I cannot open the video file without changing its name extension to .h264 Is there a way I can confirm the video file codec?

[chrisruk]

Thanks for pointing that out! That appears to be a bug too, it shouldn't be h264 data.

[davidplowman]

I remember ages ago there was a problem where the mjpeg hardware encoder wasn't (always) getting included in the firmware builds, and it would fall back to h264. Might this be the same thing?

[chrisruk]

Ah yeah it could well be that. I checked that I am still setting V4L2_PIX_FMT_MJPEG.

When using 'file' on the output it says - test.mjpeg: JVT NAL sequence, H.264 video @ L 40

[chrisruk]

Just found something interesting @davidplowman

If I add start_x=1, to /boot/config.txt I do get - test.mjpeg: JPEG image data, baseline, precision 8, 1280x720, components 3

I think that might of been the behaviour we saw before

[davidplowman]

Yes, start_x=1 will be the workaround. But I thought we'd sorted this out... evidently not. I'll have another look. Anyway, it's not a Picamera2 issue, it'll require an OS/firmware update, so no need to hold up our bugfix 0.3.5 release I think.

You can check the state of your image using v4l2-ctl -d /dev/video11 --list-formats. If that doesn't list MJPG then you'll end up with h264.

[chrisruk]

Thanks, that's a useful command to know.

Added a pull request regarding timestamps for MJPEG here - https://github.com/raspberrypi/picamera2/pull/365

[davidplowman]

Indeed there is still a problem enabling the MJPEG encoder in non-"start_x" builds. Should be fixed now, but will take a few days to appear via sudo rpi-update (usual caveats apply about that, of course).

[davidplowman]

This should be available through sudo rpi-update now if you feel like trying it. As I said, it's the bleeding edge firmware so don't try it on a system where there's stuff you can't afford to lose!